I added a quests screen which can be accessed from the single player submenu, which allows the player to see which are quests are available, and which have already been completed (if they are completed the icon becomes grayed):

I could conceivably add something similar for achievements to the main menu, and an event-like popup would tell the player when they unlocked an achievement. One example of an achievement could be one that is gotten by defeating the raider player during the A Bargain is Struck quest in the Chaincolt Foothills map, instead of just transporting the caravans and the envoy to safety.